Catheters are commonly used for advancement into a body passage for purposes such as diagnosis or treatment of medical conditions. Examples of such passages include but are not limited to a carotid artery, coronary artery, femoral artery, other blood vessel, a ureter, urethra, bronchus, esophagus, or other passage. Examples of such catheters include but are not limited to diagnostic, guide, balloon (PTCA, PTNA or PTA), stent delivery (BES, SES or DES), drug delivery, infusion, aspiration, atherectomy, thrombectomy, embolic protection device delivery, embolic protection device recovery, and others. Such catheters are typically used by first advancing a guidewire into the body passage, backloading the proximal end of the guidewire into the distal end of a catheter lumen, and advancing the catheter over the guidewire to a region of interest.
It is not unusual for the body passage to be partially obstructed due to atherosclerotic disease, tumors, mechanical causes (May-Thurners syndrome), or other causes. Advancing catheters past the obstruction can be difficult and time consuming. Part of the problem is that in conventional catheters there is generally not a smooth transition from the guidewire outer diameter to the catheter outer diameter. The mismatch between said diameters becomes an impediment to successful catheter advancement across an obstruction.
There are some catheters in the market addressing the problem of advancement past an obstruction but they are generally expensive and their results are operator dependent. For example, steerable catheters have been tried, as well as laser catheters and blunt dissectors. Both of these latter approaches carry a risk of perforation of the passage wall, and ablative technologies generate potentially harmful ablated materials.
Another problem encountered with these catheters is that the backloading of guidewires into catheter lumens can be difficult due to dim lighting in most catheterization labs and farsightedness of older practitioners. There have been some accessory devices marketed to simplify the process of backloading guidewires into catheter lumens but none have seen widespread adoption in the market.
What is needed is a catheter having improved ability to cross body passage obstructions and a catheter that more easily allows backloading of a guidewire into the lumen of the catheter.